Antiallergenic agent

ABSTRACT

House dust mite allergens and plant allergens are removed by treatment with tannic acid solution. A miticide may be included to kill dust mites. A preferred miticidal antiallergenic agent comprises benzyl alcohol, ethanol, tannic acid and water.

This is a continuation of application Ser. No. 753,215, filed 7-9-85,now abandoned.

FIELD OF THE INVENTION

The present invention relates to the use of tannic acid to removeallergens from an environment.

PRIOR ART

Diseases thought to have an "allergic" basis such as asthma, hay fever,eczema and urticaria have plagued man for a long time. In the past fewdecades it has become clear that house dust mites are extremelyallergenic and there is now evidence that continued avoidance of contactwith these allergens may result in a decrease of bronchialhyperreactivity in mite sensitive asthmatics. Attempts have been made toprevent contact with allergens by employing air filters, special vacuumcleaners, mattress covers etc., but so far the results have beendisappointing.

The house dust mite D. farinae and D. Pteronyssinus can live inblankets, sheep skins and probably in any place where human skin scalesor other mite fodder can accumulate, including house dust. Simplykilling the mites in these places does not necessarily reduce theallergens in the environment because dead mites remain allergenic andcan slowly release more allergen as they break down. It is obvious thatan agent which could destroy the allergenic material in dusts, blanketsand bedding, would be of great value.

During a preliminary investigation into the chemical nature of miteallergens it was observed that common oxidising or reducing agents,divalent and trivalent cations, alkalis, aldehydes and mild acids had noeffect on the allergenicity of house dust mite allergens. Other workershave reported that the allergens have the ability to withstand evenproteolytic digestion. Thus the allergens appear to be very stable andthis no doubt contributes to their persistence in the environment.

AIM OF THE INVENTION

The invention aims to provide an effective antiallergenic agent.

SUMMARY OF THE INVENTION

The present invention provides a method of removing allergens from anenvironment, which comprises treating the environment with tannic acid.

The invention also provides an antiallergenic composition whichcomprises tannic acid and a carrier.

Generally, the composition comprises 0.1-10 wt% tannic acid; preferablyabout 1 wt%.

The composition may be in the form of a liquid, spray, aerosol, or anyother convenient form. An aqueous solution is generally preferred.

Alternatively, the air in the environment may be passed through a tannicacid treatment screen to remove allergens, e.g. by bubbling the airthrough a tannic acid solution. A suitable device for treating the airmay be incorporated in a conventional air conditioning system.

The composition might be used to wash allergen--contaminated walls,floors, clothing, bedding pillows, curtains, floor coverings or anyother washable parts of the environment.

Tannic acid has been shown to have no substantial discolouring effectson light coloured carpets and fabrics. Any slight discolouration couldbe easily removed by rinsing in water.

It is preferred to treat the area with an insecticide (i.e. miticide) tokill living mites, before applying the tannic acid to reduce theallergenicity of the mite debris. Conventional insecticides such aspyrethrins, pyrethroids or organophosphorus compounds may be used.However, alcohols such as ethanol and benzyl alcohol have been found tobe particularly effective as miticides. A composition comprising atleast 10 vol% benzyl alcohol has been found to be especially good. Asurfactant may be included also.

A preferred miticidal composition comprises a 0.5 to 5% w/v solution oftannic acid in a solvent comprising:

ethanol 0.20-40% v/v

water 0.50-70% v/v

benzyl alcohol 0.5-20% v/v

Tannic acid applied as a 1 wt% aerosol was found to be non-irritating tothe human upper respiratory mucosa or lungs.

Treatment with tannic acid has been found to substantially reduce mostallergens. House dust allergens and some plant allergens may be almostcompletely removed. Food allergens may also be treated.

Procedures for chemically altering protein material have been known forcenturies. The tanning of animal hides to make leather is an example,and recently artificial horn and tortoiseshell have been made bytreating gelatin and albumin with tannic acid. Tannic acid has been usedto alter chemically the molecular surface on cell membranes to permitthe bonding of antibodies in agglutination assays. The tanning processin general involves the introduction of polymerising phenol groups and areduction in protein bound water. As a result the protein becomesinsoluble and more hydrophobic.

DESCRIPTION OF EXPERIMENTAL WORK

The invention will now be further described by way of example only.

I. TREATMENT WITH TANNIC ACID SOLUTION Experiment 1.

Effect of tannic acid on house dust allergen

Two 0.42 g samples of house dust which contained 2666 Dermatophagoidespteronyssinus mites per gram were placed in tubes A and B. Seven ml ofdistilled water were added to A and 7 ml of 1% aqueous tannic acidsolution were added to B. The samples were shaken for 3 minutes and letstand for two hours, after which the supernates from both samples wereused to skin test a subject known to give positive skin reactions tohouse dust mites. Distilled water was used as a negative skin testcontrol. All test were repeated six times.

Experiment 2

Dialysis of tannic acid treated house dust

Samples A and B from Experiment 1, i.e. dust extracts with and withouttannic acid and containing suspended dust material were dialysed againstcold distilled water for 72 hours to remove tannic acid, and the skintests using these samples were repeated.

Experiment 3

Some D. pteronyssinus extract was treated separately with 1% and 2%tannic acid in 0.25% aqueous solution of a common laundry detergent andtested for skin reaction. D. pteronyssinus extract plus detergent wasused as a positive control.

Experiment 4

Effect of detergent on allergens previously treated with tannic acid

A dust sample that had had its allergens removed by 1% tannic acid wastreated with 0.25% laundry detergent and skin tests again performed.

Experiment 5

Plant allergens and tannic acid

Commercial extracts of the grass Phleum pratense and the weed Plantagolanceolata were dialysed until free from glycerol and treated with 1%tannic acid and skin tests performed as before.

Results

The results of the skin tests are shown in Table I.

                  TABLE I                                                         ______________________________________                                        Test No.                                                                             Skin Tests (weal diameter mm)                                          ______________________________________                                        Experiment 1                                                                                     House dust                                                        House dust  plus 1%                                                           plus water  tannic acid Distilled                                             (sample A)  (Sample B)  water (control)                                ______________________________________                                        1      +ve         -ve         -ve                                            2      +           -           -                                              3      +all        -           -                                              4      +5 × 5                                                                              -           -                                              5      +           -           -                                              6      +           -           -                                              ______________________________________                                        Experiment 2                                                                         Dialysed house  Dialysed house                                                dust plus water dust plus tannic acid                                  ______________________________________                                        1      +ve             -ve                                                    2      +               -                                                      3      +all            -                                                      4      +5 × 5    -                                                      5      +               -                                                      6      +               -                                                      ______________________________________                                        Experiment 3                                                                  House dust mite                                                               (D. pteronyssinus)                                                            plus detergent plus  House dust mite                                                 1%         2%         (D. pteronyssinus)                                      tannic acid                                                                              tannic acid                                                                              plus detergent only                              ______________________________________                                        1      +          -ve        +                                                2      +all       2 ×  2                                                                             +-3 +5 × 5 - +all                          4      +          -          +6 × 6                                     5      +          3 × 3                                                                              +                                                6      +          2 × 2                                                                              +                                                ______________________________________                                        Experiment 4                                                                                   Tannic acid treated                                                           house dust + detergent                                       ______________________________________                                        1                -ve                                                          2                -                                                            3                -                                                            4                -                                                            5                -                                                            6                -                                                            ______________________________________                                        Experiment 5                                                                         Timothy grass                                                                             Timothy grass                                                                             Plan- Plantago                                        (phlem)     +1%         tago  +1%                                             extract     tannic acid extract                                                                             tannic acid                              ______________________________________                                        1      +ve         -ve         +ve   -ve                                      2      +           -           +     -                                        3      +all        -           +all  -                                        4      +9 × 7                                                                              -           +7 ×                                                                          -                                                                       6                                              5      +           -           +     -                                        6      +           -           +     -                                        ______________________________________                                    

The results show that 1% tannic acid solution completely abolishes theallergenicity of house dust and the dust does not regain itsallergenicity when the tannic acid is dialysed out. If tannic acid iscombined with an alkaline laundry detergent it is only moderatelyeffective in removing the allergens but dust which has had its allergensremoved by tannic acid treatment remains free of allergen whensubsequently exposed to detergent.

The plant extracts of Phleum and Plantago also lose their allergenicitywhen treated with tannic acid.

Clearly tannic acid is able to abolish allergens in house dust and someplants, and plausibly may be effective against many more allergens.Washing articles of clothing, bedding, pillows, drapes etc. in 1% tannicacid solution may prove to be an effective way of reducing environmentalallergens. This could be particularly useful in poorer communities whereit is often uneconomical to destroy materials which are heavilycontaminated with house dust mites.

II. TANNIC ACID--MITICIDE COMPOSITION

(A) A solution has now been prepared which in the laboratory effectivelykills the house dust mites Dermatophagordes pteronyssinus andDermatophagoides farinae and also removes the allergens associated withthe mites, such as those from mite body fragments or mite faeces.Studies indicate that other allergens present may also be inactivated.

The mite killing compound which has been incorporated into the 1%aqueous tannic acid solution is benzyl alcohol, a non toxic, lowvolatile alcohol (boiling point 203°-208° C.) used in the perfume andfood flavouring industry. Benzyl alcohol was found to be most effectivein killing mites when it was used as a 10% solution or higherconcentration. To enable this amount of benzyl alcohol to dissolve inthe aqueous tannic acid solution it has been necessary to add 30% ethylalcohol as a solvent. The resultant composition is:

Ethyl Alcohol 30% v/v

Water 60% v/v

Benzyl Alcohol 10% v/v

Tannic Acid 1% w/v in the above mixture

The solution of this composition has unique properties which enhance itsuse as a miticide in household carpets etc. Namely, when the solution isapplied to a surface or fabric the initial concentration of benzylalcohol is 10% v/v. On exposure to air the ethyl alcohol component israpidly lost by evaporation. This results in the benzyl alcohol comingout of solution in the form of small well dispersed droplets which canbe readily observed under a microscope. This takes place because anaqueous solution with no ethyl alcohol in it can only hold about 4 vol %benzyl alcohol. The net effect is that as the ethyl alcohol evaporates,local high concentrations of benzyl alcohol can occur in carpet fibresetc, with consequent enhancement of its miticidal properties. Theallergen destroying properties of the tannic acid remain unaltered.

(B) Table II shows the effect of the tannic acid--ethyl alcohol--benzylalcohol--water mixture on living Dermatophagoides mites, as comparedwith some other substances tested.

                                      TABLE II                                    __________________________________________________________________________                            SURVIVAL TIME OF MITES                                NO.                                                                              SUBSTANCE TESTED     D. pteronyssinus                                                                       D. farinae                                   __________________________________________________________________________    1  KEROSENE             >4 hrs   >4 hrs                                       2  INSECTICIDE (1)      17 min   34 min                                          Tetramethrin 0.27%                                                            Phenothrin 0.95%                                                              Piperonyl butoxide 1.08%                                                   3  INSECTICIDE (2)      >1 hr    >1 hr                                           Tetramethrin 0.36%                                                            Phenothrin 0.1%                                                               Allethrin 2.8%                                                             4  SURGICAL ANTISEPTIC  >4 hrs   >4 hrs                                          Iodine 1% +                                                                   Surfactant                                                                 5  ETHYL ALCOHOL        11 min   45 min                                       6  ETHYLENE GLYCOL      >4 hrs   >4 hrs                                       7  SPRAY DISINFECTANT   11 min   36 min                                          N.alkyl dimethyl benzyl-                                                      ammonium chlorides 0.1%                                                       Triethylene glycol 8%                                                         Ethanol 37%                                                                8  METHYL BENZOATE      45 min   >45 min                                         (a veterinary miticide)                                                    9  BENZYL ALCOHOL (NEAT)                                                                               1 min    2 min                                       10 BENZYL ALCOHOL-TANNIN-WATER                                                                        2-3 min   5 min                                          ("antiallergenic agent")                                                   __________________________________________________________________________

Mites of both species proved to be extraordinarily hardy and were oftenobserved living entirely submerged by some test solutions (not givenabove) 24 hours after beginning the experiment.

(C) Because of its potency in killing mites, its low toxicity, faintpleasant odour and low vapour pressure (<1 mm Hg at 20° C.) benzylalcohol was chosen as a suitable mite killing additive to the originalaqueous tannic acid solution. Table III shows survival rates of themites D. pteronyssinus and D. farinae when exposed to tannicacid--water--alcohol--benzyl alcohol mixture on a welled glass slide.

                  TABLE III                                                       ______________________________________                                                SURVIVAL RATES OF                                                             DERMATOPHAGOIDES Spp. IN CON-                                         EXPERI- TACT WITH "ANTIALLERGINIC AGENT"                                      MENT    D. pteronyssinus D. farinae                                           NUMBER  minutes/seconds  minutes/ seconds                                     ______________________________________                                        1       2         52         7       32                                       2       3         26         7       43                                       3       4         00         6       30                                       4       3         35         7       08                                       5       3         00         7       35                                       6       3         00         9       00                                       7       3         35         9       32                                       8       3         58         10      01                                       9       4         26         8       52                                       10      3         43         7       00                                       N = 10               N = 10                                                   MEAN = 3 mins 33 secs                                                                              MEAN = 8 mins 5 secs                                     SD 30 secs           SD 1 min 19 secs                                         ______________________________________                                    

D. farinae was the hardier of the two mites but both mites were quicklykilled by the antiallergenic agent. The above experiments also showedthat benzyl alcohol retains its miticidal properties when mixed with theother components of the solution. In consequence, a mixture of benzylalcohol-tannic acid-ethyl alcohol and water in the proportions describedabove both kills mites and destroys their allergenicity. Such an agenthas wide potential application in the control of environmental allergensand could be of great benefit to sufferers of allergic diseases andasthma.

III POSSIBLE ADVERSE EFFECTS

Possible adverse effects of the solution when inhaled were sought innormal and asthmatic patients. Four moderately severe to severeasthmatics and 2 normals have been bronchially challenged withincreasing aerosolised doses of the antiallergenic agent. The doses,delivered via aerosol spray while the patient was inhaling through themouth were:

1st dose 0.003 ml (as aerosol)

2nd dose 0.009 ml (as aerosol)

3rd dose 0.015 ml (as aerosol)

The patients forced expiratory flow rates (FEV1) were measured byspirometry after each dose. No broncho-constricting effects resulted.The substances present in "antiallergenic agent" are thought not likelyto produce bronchoconstriction. In any case they would be inhaled in atreated house (if at all) in such high dose as we have used in thetests.

IV EFFECTIVENESS OF ANTI ALLERGIC AGENT IN THE FIELD

The solution known as "anti-allergenic agent" has been found to bothkill house dust mites and remove their allergenic properties underlaboratory conditions. The following is aimed at testing theeffectiveness of the solution in the field, that is, to determinewhether or not the symptoms of an allergy sufferer improve after acontrolled part of his environment, namely his home, is treated with thesolution.

Two preliminary studies have been made of two asthmatic patients.

Forced expiratory flow rates (an index of airways resistance and asthma)were measured four times daily for periods before and after the patientshouses had been treated with antiallergenic agent. Carpets, curtains,other fabrics and floors were sprayed or mopped with the antiallergenicsolution. Average percentage improvement in respiratory airflow afterhouse treatment is shown in Table IV.

                  TABLE IV                                                        ______________________________________                                        EXPIRATORY FLOW RATE        PER-                                              BEFORE HOUSE     AFTER HOUSE    CENT                                          TREATED WITH     TREATED WITH   IM-                                           ANTIALLERGENIC   ANTIALLERGENIC PROVE-                                        AGENT            AGENT          MENT                                          ______________________________________                                        Pa-   *136 (av. over 160 (av. over  17.6%                                     tient 1                                                                             6 weeks)       5 weeks)                                                 Pa-   532 (av. for   580 (av. over   9.0%                                     tient 2                                                                             1 week)        3 weeks)                                                 ______________________________________                                         *The flow rates for the two patients were measured on instruments with        different arbitrary scales and therefore are not directly comparable.         However, the percentage improvement in each patient is comparable.       

I claim:
 1. A method of removing allergens from an environment whichcomprises treating said environment with an antiallergenically effectiveamount of tannic acid in conjunction with a miticidally effective amountof miticide such as to remove said allergens from said environment,wherrein the allergens are selected from the group consisting of housedust mite allergens selected from the group consisting of D. farinae andD. Pteronyssinus.
 2. A method according to claim 1, wherein theenvironment comprises air.
 3. A method according to claim 1, whereinsaid tannic acid is contained in an amount of 0.1 to 10 weight %.
 4. Amethod according to claim 1, wherein the miticide is selected from thegroup consisting of conventional insecticides and alcohols.
 5. A methodaccording to claim 4, wherein the insecticide is selected from the groupconsisting of pyrethrins, pyrethroids and organophosphorous compounds.6. A method according to claim 5, wherein the tannic acid is in a 0.5 to5% w/v solution in a solvent comprisingethanol 20 to 40% v/v water 50 to70% v/v benzyl alcohol 5 to 20% v/v.
 7. A method according to claim 6,wherein 1% v/v tannic acid is in a solvent comprising30% v/v ethanol 60%v/v water and 10% v/v/benzyl alcohol.
 8. A method according to claim 4,wherein the alcohol is selected from the group consisting of ethanol andbenzyl alcohol.
 9. A method according to claim 4, wherein the alcohol isbenzyl alcohol.
 10. An aqueous composition adapted for removal ofallergens from an environment, said allergens being house dust miteallergens selected from the group consisting of D. farinae and D.Pteronyssinus, which comprises an admixture of the followingcomponents:(a) 0.1 to 10 weight % tannic acid, (b) a miticidallyeffective amount of benzyl alcohol and, (c) an environmentallyacceptable aqueous carrier.
 11. A composition according to claim 10which comprises a 0.5 to 5% w/v solution of tannic acid in a solventcomprisingethanol 20 to 40% v/v water 50 to 70% v/v and benzyl alcohol 5to 20% v/v.
 12. A composition according to claim 11 comprising30% v/vethanol 60% v/v water 10% v/v benzyl alcohol and 1% v/v tannic acid.